Chain saw



United States Patent [72] Inventor Patented Aug. 25, 1497() Sheel L of 4 ,INVENTOR ATTORNEY BY nu L.) Roue/P1.

Parental Aug. 25, 1970 13,525,373

Sheet 2 of 4 INVENTOR ATTORNEY Paiennted Aug. 25, 1970 Sheet 3 of' 4 INV ENTOR ATTORNEY Patented Aug. 25, 1970 INVENTOR ATTORNEY CHAIN sAw The present invention relates to a vibration-proof chain saw in which an improvement is made in the arrangement of the constitutional elements.

Chain saws are being popularly used as a forestal tool but the vibration originated from the engine and the saw chain gives an objectionable influence on the body of the user, frequently causing a physical disorder.

The object of the present invention, therefore, is to provide an improved chain saw which obviates such constructional defect of conventional chain saws and minimizes the vibration which is transmitted to the user during operation.

According to the present invention, there is provided a chain saw in which vibrating elements, such as engine and saw chain, which are the sources of vibration, and all other stationary elements, such as machine frame and fuel tank, etc., are provided in two blocks independent of each other in such a manner as to make the total weight of said stationary elements as large as possible with respect to the weight of the entire chain saw, and both blocks are combined together through the intermediary of elastic shock-absorbing members, whereby the amount of vibration generated by said vibrating elements and being transmitted to the user through a handle is reduced drastically as compared with the conventional chain saws.

The present invention will now be described with reference to the accompanying drawings in which the present invention is illustrated by way of example and in which:

FIG. 1 is a perspective view of the chain saw according to the present invention;

FIG. 2 is a vertical cross section of the chain saw taken on the line II-II of FIG. 3;

FIG. 3 is a top plan view, partly broken away, of the chain saw;

FIG. 4 is a front view of the chain saw with a portion shown in section;

FIG. 5a is a view of one form of the shock-absorbing member used in the chain saw of this invention; and

FIGS. 5b and Sc respectively are views of other fonns of the shock-absorbing member.

Referring to the drawings, a guide bar 30 for guiding a saw chain 29 is held between side plates 3l and is secured fastly to a crank chamber on the transmission side by a guide bar holding member 13 and bolts 13. The saw chain 29 carries a number of cutter blades 29' thereon and is driven by a sprocket to travel along the periphery of the guide bar, said sprocket being mounted on an output shaft of a prime mover 12 through a centrifugal clutch. The prime mover 12 consists` of an air-cooled, two cycle, single cylinder gasoline engine. The cylinder 1 and piston 2 of the engine are made of an aluminum alloy with a view to reducing the weight of the chain saw to a minimum. A connecting rod 3 has one end thereof` connected to the crank-pin 4 of the engine. On the exhaust side of the engine is mounted a muffler 5 as shown in FIG. 3, which muffler is made of an aluminum alloy casting. Reference numeral 27 designates a spike-bumper for the engagement with a standing timber during cutting operation and this spike-bumper is fixed to the crank chamber on the transmission side, at a point adjacent the guide bar 30. A machine frame portion, which constitutes a stationary block, includes a fuel tank 14 and an oil tank 33, and is provided with an auxiliary handle 21 in the front portion and a main handle 18 in the rear portion thereof, said main handle having one end thereof supported by a main handle supporting member 20. The main handle and auxiliary handle are respectively provided with gripping rubbers 19 and 22 thereon. Reference numeral designates a top cover, which is provided with a fuel tank cap 28 and an oil tank cap 32, and is sealably mounted on the fuel tank 14 and oil tank 33 by bolts l5. A carburetor indicated at 6 in FIG. 2 is of the diaphragm type, e.g. Tillotson HL Type or Tillotson HS Type, and is preferably connected to the suction side of the engine through a flexible suction tube 8, for the purpose of reducing the weight of the vibrating block,

though it may be mounted directly on the engine body. Between an air cleaner cover 16 having a knob 7 thereon and the carburetor 6 is interposed an air cleaner 17. Reference numeral 24 designates a throttle trigger which is connected to the throttle'valve in the carburetor by a valve actuating rod (not shown). A fan cover 11 is provided to cover a fly-wheel fan (not shown) which is connected to one end of the crank shaft and has mounted therein magneto means adapted to be energized by a recoil starter 26. The oil contained in the oil tank 33 is supplied to the saw chain through an oil tube by a manual and automatic plunger pump (not shown) of the known type.

FIG. 5a shows one form of the shock-absorbing member 23 to be used in the chain saw of this invention. This shock-absorbing member is composed of a shock-absorbing rubber block 102a which is normally in a cylindrical shape but is not necessarily restricted to that shape, and screw rods a which are each provided with a plate member 101a and are fixed to both the upper and lower ends of saidk rubber block. According to another form of the shock-absorbing member shown in FIG. 5b, end plates l04b and a spring 103b interposed between said end plates with both ends thereof soldered to the respective end plates, are integrally embedded in a shock-absorbing rubber block 1021: which is also normally in a cylindrical shape, so as to reinforce and augment the resilient force of the rubber block. The end plates 104b are soldered to plate members 101b connected integrally to screw rods l00b. According to still another form of the shock-absorbing member shown in FIG. 5c, each of the shock-absorbing rubber blocks 102e has the plate member 101e` of a screw rod 100e` attached to the outer end and a plate member 104e` attached to the inner end thereof, and a spring 103e is interposed between the opposed plate members 104C with both ends thereof soldered to the respective plate members.

As described hereinabove, since, according to the present invention, the vibrating block comprising the engine, saw chain and guide cover, etc. is separated from the stationary block comprising the other stationary elements, in such a manner as to make the weight ratio of the vibrating block to the entire chain saw as small as possible, and both blocks are combined through a plurality of the aforesaid shock-absorbing members 23, it is'possible to prevent the vibration of the engine, etc. from being transmitted to the handles on the stationary block and therefore to carry out the cutting operation with ease, without imposing an objectionable influence on the user.

In mounting the shockabsorbing member 23, one of the screw rods thereof is screwed into an internally threaded hole 34 formed in the wall 9 of engine crank chamber, while the other screw rod is inserted through a bolt hole 35 formed in the machine frame and tightened by a nut 36, so that both end surfaces of the shock-absorbing member are pressed against the mounting surfaces of the wall of crank chamber and the machine frame respectively. As shown in FIGS. 2 and 3, a part of the mounting seat 25 provided on the machine frame extends downwardly to surround the cylindrical body of the shock-absorbing member 23. The inner peripheral wall 25' at the top end portion of the mounting seat is in substantially flush contact with the peripheral wall at the top end portion of the cylindrical body of the shock-absorbing member but expands progressively downwardly to form a small gap e between the lower end portion thereof and the peripheral wall of said cylindrical body of the shock-absorbing member, said gap being normally of the order of about 3 mm. Such configuration of the mounting seat provides for a lateral displacement, within a prescribed range, of the shock-absorbing member as caused by a shearing force imposed thereon due to the vibration generated in the vibrating block, but prevents a lateral displacement of the same in excess of said tolerable range or deformation of the same.

Although the present invention has been described and illustrated in terms of a specific embodiment thereof, it is to be understood that many modifications and changes are possible in the embodiment without deviating from the scope and spirit of the invention as set forth in the appended claims.

Iclaim:

l. A chain saw wherein the constitutional elements of the chain saw are segregated into a vibrating block including an engine and a chain saw, and a stationary block including a fuel tank, oil tank, a main handle and an auxiliary handle oriented in a manner such that the weight ratio of the vibrating block with respect to the total weight of the entire chain saw can be reduced to a minimum, both of said blocks are connected through the intermediary of a plurality of shock-absorbing members, each shock-absorbing member comprising a block of resiliently compressible material, each shock-absorbing member including plate-and-rod means including a portion projecting from the same between said vibrating and stationary blocks so as to prevent vibration of the vibrating block from being transmitted to said stationary block and the handles thereof, and spring means integrally connected to said block of resiliently compressible material for supplementing the shock-absorbing characteristics of said members.

2. A chain saw claimed in claim 1 wherein said spring means comprising a compression spring embedded within said block of resiliently compressible material.

3. The chain saw of claim 1 wherein said resiliently compressible material comprises two spaced segments each of which having rod means connected thereto and projecting away from each other in axial relationship, said spring means being interposed between said separate blocks of resilient material and terminally connected thereto.

4. A chain saw wherein the constitutional elements of the chain saw are segregated into a vibrating block including an engine and a chain saw, and a stationary block including a fuel tank, oil tank, a main handle and an auxiliary handle oriented in a manner such that the weight ratio of the vibrating block with respect to the total weight of the entire chain saw can be reduced to a minimum, both of said blocks are connected through the intermediary of a plurality of shock-absorbing members, each shock-absorbing member comprising a block of resiliently compressible material, plate members secured to said block at opposite ends thereof respectively and a rod member tixedly mounted on each of said plate members and extending outwardly therefrom, said stationary block includes an opening forming a recess confronting said vibrating block, said recess being complementary to said block of resilient material and telescopically receiving the same, said block of resilient material projecting from the recess into engagement with said vibrating block, one of said rod members being terminally connected to the vibrating block and the other of said rod members being terminally connected to the stationary block, said recess being relieved at an intermediate portion of said block of resilient material to define a small gap between a portion of the inner wall of the recess and a portion of the outer peripheral surface of said block, thereby permitting a limited amount of lateral displacement due to shear forces imposed thereon when vibrations are generated by said vibrating block, and preventing lateral displacement over a prescribed range. 

